Balance bar for watches



Jan. 12, 1954 VAN HAAFTEN 2,665,546

BALANCE BAR FOR WATCHES Filed April 29, 1952 FIG.3

INVENTOR EGBERT VAN HAAFTEN ATTORNEY Patented Jan. 12, 1954 BALANCE BAR FOR WATCHES Egbert Van Haaften, Lancaster Township, Lancaster County, Pa., assignor to Hamilton Watch Company, Lancaster, Pa.

Application April 29, 1952, Serial No. 284,854

2 Claims.

This invention relates to a balance bar to be used in place of the balance wheel in watches.

The object of the invention is to provide a bar mounted on a central stair which will take the place of the balance wheel of a watch and which need be poised in only two positions.

A still further object of the present invention is to provide a balance bar for watches having a relatively thin resilient cross arm capable of deformation with relatively heavy short are like sections located at opposite ends of the cross arm.

It is a still further object of the present invention to provide weight adjusting means which are housed in the short heavy are shaped sec tlons.

The invention is shown in the accompanying drawing in which:

Figure 1 is a perspective view of the balance bar.

Figure 2 shows the balance bar in position for horizontal poising.

Figure 3 shows the balance bar in position for vertical poising.

Figure 4 shows a modification of the arcshaped section.

A balance staff 8 formed with the ordinary pivots 9 is secured at its center position to a cross arm ill. The roller, generally part of the arm, is omitted from this drawing as well as the specific means for staking the staff to the cross arm. The cross arm I is formed with the central substantially circular portion ll, narrowed neck portions 12, and widened ends I3. The end sections may be formed with holes 14 to reduce the weight of the cross arm.

Arcuate shaped end blocks l have feet 15 integral therewith and are formed with a central threaded well !7. The arcuate shaped blocks are secured to the end portions l3 of the bar so that the outer edge of the bar and the outer edge of the end block coincide, the feet I 6 fitting in holes within the bar. These feet are riveted or upset to secure the blocks to the bar. Threaded in the well ll are plugs I8 which may be moved toward or away from the center of the bar to vary the moment of inertia of the balance bar or to poise the bar when in horizontal position.

Referring particularly to Figure 2, the bar I6 is shown balanced on knife edges 9 for horizontal poising. The screw plugs 18 are adjusted to poise the bar in the horizontal position.

Referring to Figure 3, the balance wheel is again shown poised on knife edges 2!] but in a vertical position. Any tendency of the bar to turn either clockwise or counterclockwise is counteracted by bending the bar manually at the points I2, as shown slightly exaggerated in Figure 3. This shifts the weight of the block, either upper or lower depending on which one is bent, slightly to one side or the other of a physical center line and produces a bar which is poised in a vertical position. It is only necessary to poise the bar in th vertical position and the horizontal position to have a perfectly poised instrument.

An indexing mark 2| may be used with the scale 22 on the head of the screw to move each of the pair of screws inward or outward the exact same distance, so that after poising it is possible to change the moment of inertia without afiecting the poise of the balance bar by moving the opposite screw plugs an equal distance.

Referring particularly to Figure 4., a modification is shown in which a screw 23 having an eccentrically mounted head 24 is threaded into a hole 25 in a well 26 in one side of the block 15'. This eccentric screw may be turned to throw the weight of the head away from or toward the vertical center of the bar so that in poising of the vertical position, a fine adjustment may be had by turning this screw less than a turn to throw its weight to one side or the other. This adjustment may complement the bending shown in Figure 3 or may be used entirely in place of this method of bringing the balance bar to a vertical poised position.

What is claimed is:

1. A balance assembly for watches, comprising a balance staff, a cross arm centrally secured to said balance staff, a pair of weights on opposite ends of the balance arm, means carried centrally of said weights and in line with said balance arm for poising said balance when the arm is in a horizontal position. said balance arm being substantially reduced in width at points on opposite sides and adjacent the to permit the arm to be bent at an angle to its longitudinal axis to permit poising of the balance assembly when the arm is in a vertical position.

2. A balance arm assembly according to claim 1 and including an eccentric screw threaded into one of the weights, said screw being rotatable to shift its weight closer to or farther away from the longitudinal axis of the cross arm to permit poising in a vertical position, the weight being substantially the same distance from the staff in all positions to permit poising without changing the moment of inertia.

EGBERT VAN HAAFTEN.

References Cited in the file of this patent UNITED STATES PATENTS Number Name 7 Date 965,506 Ecaubert July 26, 1910 2,430,628 Whitehead Nov. 11, 1947 FOREIGN PATENTS Number Country Date 256,620 Great Britain -s Sept. 30, 1926 188,077 Switzerland 1. Mar. l, 1937 217,811 Switzerland Feb. 16, 1942 264,669 Switzerland Jan. 16, 1950 

